1. Field of the Invention
The present invention relates to an oil filter wrench. More specifically, the present invention relates to methods and apparatus for a wrench used with a seized conventional engine oil filter that incorporates a plurality of threaded shaft and nut assemblies employed to lock the wrench to the seized oil filter for maximizing the torque applied to the seized oil filter when the wrench is rotated.
2. Description of the Related Art
Modern engines utilized in automobiles, emergency power generating stations and the like employ a conventional oil filter element for filtering the oil. The oil filter element is contained within a housing. The oil filter housing typically includes an arrangement of intake and output ports for receiving and exhausting a supply of lubricating oil to be filtered. Further, the oil filter is typically secured to the side of the engine block by metallic threads, e.g., the oil filter is threaded onto the engine block.
The oil filter housing is comprised of a thin metallic enclosure having a closed end and an open end. The enclosure includes a plurality of (e.g., typically 14-16) edges or lugs at the closed end designed for grasping and rotating the filter housing. The open end of the filter housing includes an arrangement of intake and output ports and a thread engagement arrangement each known in the art. The threads on the filter housing and the threads on the oil filter mount on the engine are engaged and the filter is secured in position by rotation of the filter. Removal of the filter is accomplished by rotation of the filter housing in the opposite direction. Thus, this type of conventional engine oil filter is referred to as a "spin-on" filter.
A set of manufacturer's instructions normally are supplied with the purchase of a new conventional spin-on oil filter. The instructions typically recite a procedure for installing and removing the oil filter. Attached to the open end of the oil filter is an oil seal designed to prevent leakage of oil from the filter during use. The instructions for the installation of the spin-on oil filter typically direct the installer to rotate the filter housing an additional 3/4-to-1 turn after the oil seal initially touches the base of the oil filter mount on the engine. The filter installation is usually accomplished by use of a conventional oil filter installation tool known in the art.
Occasionally, an installer decides that the additional 3/4-to-1 turn of the filter housing (after the oil seal initially touches the base of the oil filter mount) suggested by the manufacturer during installation is insufficient to avoid oil leakage or loss of the filter element. Thus, a typical installer of average strength can easily over-tighten the filter housing using only nominal torque with the conventional installation tool. This snug or over-tightening of the filter housing beyond the recommended number of turns often leads to the condition of a seized or over-torqued oil filter when oil filter element replacement is attempted.
Several factors contribute to the seized or over-torqued filter condition. Some of these factors are directly related to the characteristics of a new filter versus a used filter. For example, less torque is required to install a new oil filter housing because the components, such as the oil seal, have not yet been expanded. The expansion of the oil seal in a used oil filter typically results in more torque being required to remove the filter housing. A major factor contributing to the seizure of filter elements is the engine heat to which the filter housing is subjected. The components of the oil filter are subjected to thermal expansion due to the heat from the engine. The thermal expansion in combination with oil saturation of the filter components over time results in more torque being required to remove the filter housing. Further, failure to lubricate the oil seal during installation often results in seizure of the filter element due to the thermal expansion of the filter components.
In the past when an oil filter housing was over-torqued and seized to the oil filter mount on the engine, removal of the filter element was very difficult and time consuming. The only available means of removing the seized filter housing was to attempt to manipulate the filter housing with screwdrivers, chisels, hammers and the like. Often these tools are insufficient to remove the seized filter housing because of space limitations and thus adequate leverage could not be achieved. The seized oil filter was often mutilated and removal became impossible.
Over time, many types of oil filter wrenches have been developed to install and remove oil filters. These conventional oil filter wrenches include, for example, a cup type wrench, a band type wrench, a chain type wrench, a strap type wrench and a clamp type wrench. The cup type wrench typically fits over the end of the filter by mating the keyed edges of the wrench with the 14-16 edges or lugs formed on the closed end of the filter housing. The cup type wrench is then rotated to install and remove the oil filter.
However, experience has shown that the cup type wrench has severe limitations. The keyed edges of the cup type wrench are formed of steel or cast aluminum construction. When the keyed edges of the cup type wrench are mated with the softer thinwalled construction of the oil filter housing, the amount of rotational torque that can be applied is limited. The limit on the permissible rotational torque can easily be exceeded when the filter housing is being removed. The edges or lugs formed on the filter housing can be rounded off when the cup type wrench slips off of the filter housing. This condition further reduces any chance of the removing a seized oil filter from the engine block. This left the mechanic with no other alternative than to attempt to remove the filter housing with screwdrivers, chisels, hammers and the like.
Each of the conventional band type, chain type and strap type wrenches include a band, chain or strap, respectively, that is wrapped around the circumference of the oil filter housing. In the conventional band type wrench, the band is typically comprised of flexible steel having a smooth surface. Therefore, the gripping surface of the band is smooth. Consequently, the flexible band will slip around the circumference of the filter housing upon attempting to remove an oil filter that is seized in position. The chain type wrench is similar in construction to the band type wrench except a chain is utilized in lieu of the flexible steel band. The chain type wrench might provide some additional clamping force on the filter housing when compared to the smooth gripping surface of the flexible steel band. However, the chain type wrench is not effective in removing a seized oil filter that was over-torqued when initially installed.
The strap type wrench utilized to install and remove oil filters typically includes a web band comprised of flexible material. A material normally utilized for this application is nylon which is, of course, a strong synthetic material. However, the nylon material suffers from the same drawbacks as does the flexible steel band in that the nylon strap has an essentially smooth surface. Consequently, when the nylon strap type wrench is used to remove an oil filter, it is usually ineffective if the filter housing is seized. As more torque is applied to the filter housing via the wrench handle, the rotational torque limit is eventually exceeded and the nylon strap slips around the circumference of the filter housing. The clamp type wrench includes a construction that attempts to clamp around either the bottom or side of the filter housing. Because the surface of the oil filter housing is smooth, the clamp type wrench tends to slip when rotated. This, of course, is not effective when attempting to remove an oil filter when the filter housing is seized.
Another problem associated with utilizing conventional oil filter wrenches is space limitation caused by obstructions, particularly when dealing with automotive applications. Automobile components such as the exhaust manifold, exhaust pipes, oil pan, body, frame and other components tend to limit the available space to operate the conventional style wrench. Each of the conventional oil filter wrenches includes a handle which is either attached to or closely connected to the wrench. Therefore, the side components of the engine and automobile tend to obstruct the operation of the handle of conventional wrenches from the side. The side obstructions in combination with the slippage of the conventional oil filter wrench about the oil filter housing results in the inability to remove a seized oil filter.
Thus, there is a need in the art for an improvement in wrenches that are utilized with engine oil filters and particularly with engine oil filters that are seized, over-torqued or otherwise cannot be removed from an oil lubricated engine where the improved oil filter wrench would achieve a positive lock on the seized oil filter for maximizing the torque applied to the seized oil filter when the oil wrench is rotated.